1. Technical Field
The present invention relates to an illumination apparatus. More particularly, the present invention relates to an illumination apparatus with variable color temperature.
2. Description of Related Art
With the advance of technology, demands of illumination for users increase daily, and requirements of illumination quality for users gradually increase as well. Recently, traditional light sources have been replaced by light-emitting diodes (LEDs) gradually because the LEDs have advantages such as better light-emitting efficiency, long lifetime, high reliability, small volume, etc., compared to the traditional light sources, and thus the LEDs are widely applicable.
For a present illumination apparatus which is capable of generating white light, an operation of light mixture is performed with a device for generating warm white light and a device for generating cold white light such that the illumination apparatus can emit corresponding white light according to different configurations.
However, in the aforementioned operation, a chromaticity coordinate point on a CIE chromaticity diagram, which represents the white light formed by light mixture, usually cannot be accurately located on a Black Body Locus (BBL) such that the color of the white light formed according to the aforementioned operation has an apparent deviation.
Furthermore, when the illumination apparatus emits corresponding white light according to different configurations, the light-emitting devices therein must be controlled to be fully bright or fully dark, and thus the aforementioned operation of light mixture cannot be performed flexibly and the color of the white light formed by the operation of light mixture will be non-uniform.
Moreover, in order to place the devices which generate the warm white light and the cold white light in a same lamp for convenience of the operation of light mixture, a large number of LEDs have to be disposed in the same lamp based on the aforementioned operation, thereby causing an increase of the production cost and further resulting in an expensive price of the illumination apparatus, and even the size of the illumination apparatus itself cannot be significantly reduced.